Fuel injection system for engines



June 1965 J. E. YINGST ETAL FUEL INJECTION SYSTEM FOR ENGINES 4 Sheets-Sheet 1 Filed Sept. 22, 1961 June 1965 J. E. YING-r ETAL FUEL INJECTION SYSTEM FOR ENGINES Filed Sept. 22, 1961 4 Sheets-Sheet 2 47 INVENTORS 48 BY flare/d ,Qjye

A Tromgys im 8,1965 J. E. YINGST Em 3,181,734

FUEL INJECTION SYSTEM FOR ENGINES Filed Sept. 22. 1961 4 Sheets-Sheet 3 BY #47 0 d Rj id June 8, 1965 J. E. YINGST ETAL $187,734

FUEL INJECTION SYSTEM FOR ENGINES Filed Sept. 22, 1961 4 sh ets-ghee; 4

l ia V '27;

r I v a Y INFENTORS wizzfzf-Rtzze ATT NEYS United States Patent 3,187,734 FUEL INJEQTIGN SYSTEM FUR ENGENES James E. Yingst, Euclid, and Hamid R. Scihbe, Chardon, ()hio, assignors to Thompson Ramo Wooldridge Inc, Cleveland, Ohio, a corporation of @hio Filed Sept. 22, 1961, Ser. No. 139,911 7 Claims. (Cl. 123-179) The present invention relates to improvements in fuel injection systems for high speed, four cycle, spark ignition internal combustion engines and is particularly concerned with a method and mechanism for increasing the fuel delivered to the engine for starting.

The invention contemplates an embodiment in a fuel system having a variable output metering pump such as that employing reciprocating pistons delivering to a pump chamber. A distributor receives fuel from the pump and provides for periodic releases of the fuels to lines leading to fuel injectors. In a conduit means between the pump and distributor is connected an accumulator chamher which has a movable wall biased to discharge to the distributor for each fuel release and to accumulate fuel from the pump between releases. The accumulator has a biased discharge pressure in excess of the release pressure of the injector nozzles. A supply pump maintains a supply of fuel from a tank to the metering pump bypassing excess fuel not used by the metering pump.

A feature of the invention is the provision of a method and mechanism for delivering excess fuel during cranking by delivering directly to the injectors from another source, such as an arrangement whereby the output pressure of the supply pump can be increased during cranking of the engine so that the pressure will be in excess of the release pressure of the injector nozzles and fuel will flow directly through the pump chamber independent of the metering pump and be released by the distributor to be delivered through the injectors.

A further feature of the invention is the provision of a method and mechanism utilizing the metering pump for starting enrichment by the use of a system wherein the metering pump is designed for a maximum delivery in excess of the fuel requirement for maximum power operation, such as three times that required for maximum engine power output. During cranking the pump delivers at maximum output and a mechanism operating on an engine parameter (such as engine oil pressure or engine manifold vacuum) limits the metering pump output to maximum power requirements after starting (less than maximum pump output), so that an excess of fuel is available for starting Without providing additional supply mechanism.

Starting a cold engine, particularly in winter climates, requires substantially greater quantities of fuel per cylinder charge that at any other operating condition. The present invention embodies a method and mechanism capable of increasing fuel delivery by either the two above methods or by a combination of the two methods.

An object of the present invention is to provide an improved method and mechanism for a fuel injection system for delivering substantially greater quantities of fuel per cylinder charge during starting than during other operating periods.

A further object of the invention is to provide an improved mechanism for a fuel injection system having a metering pump and a distributor delivering increased fuel during starting utilizing the metering pump of the system.

A still further object of the invention is to provide a fuel injection system with fuel starting enrichment features wherein the supply pump of the system is utilized independent of the metering pump during short periods of time for delivering directly to the injectors.

A further object of the invention is to provide an improved method and apparatus for a fuel injection system using a reciprocating metering pump wherein fuel is flushed through the pumping chamber of the pump during cranking to eliminate the formation of vapor and air pockets.

(Ether objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings, in which:

FIGURE 1 is a vertical sectional view takenthrough a metering pump and distributor assembly constructed in accordance with the principles of the present invention;

FIGURE 2 is a vertical sectional view taken substantially along line 11-11 of FIGURE 1;

FIGURE 3 is a vertical sectional view taken substantially along line IIIIII of FIGURE 1;

FIGURE 4 is a schematic showing of mechanism for increasing fuel delivery during cranking of the engine;

FIGURE 5 is a vertical sectional view taken substan tially along line VV of FIGURE 1;

FiGURE 6 is a schematic showing of additional mechanism for increasing the fuel delivery to the engine during cranking; and

FIGURE 7 is a horizontal sectional view taken substantially along line VIIVII of FIGURE 1.

As shown on the drawings:

FIGURE 1 illustrates a mechanism having a pump It with a variable delivery for pumping fuel. The fuel flows to a distributor 11 which at intermittent periodic intervals releases the pumped fuel to individual fuel injectors 14 which supply an internal combustion engine. The fuel flows from the pump to the distributor through a conduit means 12 and communicating with the conduit means is an accumulator 13 which collects the fuel from the pump between distributor releases and completely discharges its collected fuel during the periods of distributor release.

Also communicating with the conduit means 12 is an enrichment device 15 which is filled with fuel from the metering pump 10 and selectively discharges this fuel to the distributor 11 when the engine is accelerated.

As will be described laterin detail, the metering pump I'll has a capacity substantially in excess of the fuel requirement for mam'mum power operation of the engine, preferably three times the maximum capacity required for engine operation. In the arrangement shown in FIGURE 4, during cranking the pump is automatically shifted to its maximum delivery for increase in fuel delivered to the engine. This is accomplished by a solenoid motor 12' drawing a control rod 13' to a maximum .pump delivery position. When the engine is started, a mechanical stop 14- limits the movement of the control rod 13' to a stroke no further than the maximum power requirement.

As shown in FIGURE 6, a further mechanism is employed for increasing fuel delivery during starting and this mechanism may be used in addition to orsepara-te from the mechanism of FIGURE 4. A supply pump 15' delivers to the metering pump it? to maintain a constant supply of fuel from the fuel tank at the metering pump intake 18. The excess fuel is delivered back to the fuel tank through a by-pass line 16. During engine crank-ing a by-pass shut-off valve 1'7 is closed so that the pressure of the supply pump builds up higher than the opening pressure of the injectors 14 so that fuel is delivered directly from the supply pump 15 through'the distributor to the injectors 14. When the engine is started, the by-pass valve 17' again opens so that the quantity of fuel delivered is determined solely by the metering pump.

Ii. Before proceeding to a detailed review of the construction and operation of the starting enrichment mechanisms of FIGURES 4 and 6 a description of the details of the metering pump and distributor mechanism will be presented.

The metering pump 10 and distributor 11 are incorporated in a unit housing 16 made up of parts which are suitably clamped together such as by cap screws or bolts with the parts having gaskets therebetween. These parts need not be described in detail inasmuch as their construction will be apparent from the drawings and the entity may be generally referred to as the housing 1 6. The housing is adapted to be suitably mounted on an engine and a pump shaft 17 is driven by the engine such as by being connected to the timing shaft. The mechanism has the distributor shaft 17 which is driven at one half the speed of an engine to which fuel is delivered so that in a four cycle engine the distributor 11 will release fuel once for one injection per four stroke cycle of the'typical multicylinder engine.

Fuel is received through a line connected to a fuel intake opening 18 in the housing 16 and usually. fuel will be delivered to the apparatus from a fuel tank by the supply pump so that the intake 18 Will receive pressurized fuel. The distributor is connected to individual fuel lines 19a which lead to the injectors 14.

The metering pump 10 is driven from the distributor shaft 17 which is supported in the housing 16 in a ball bearing assembly 18 and a cylindrical bearing surface 19. A circular sealing ring 20 is positioned around the shaft in the housing to prevent the escape of lubricant and a ring 21 is also positioned around the shaft to prevent the escape of fuel from the distributor 11, as will later be described.

The pump 10 is driven by a gear 22 on the shaft 17 driving a gear 23 pinned to the pump shaft 24 which is supported in a ball-bearing assembly 25, FIGURES 1 and 5.

The ratio of the gear 22 on the shaft 17 to the gear 23 on the pump shaft is preferably one which cannot be expressed exactly in whole numbers, such as 23/ 30 or 30/23; 25/28 or 28/25; 20/33 or 33/20. Inasmuch as pump is a piston type, such fractional gear ratios will preclude the possibility of any one piston consistently delivering fuel through the same port of the distributor and hence to the same engine cylinder. If small differences exist between the pistons, piston chambers, piston stroke links or seals of the pumping element a slight inequality of fuel delivery may occur between pistons and thiswill not consistenly result in the inequality being reflected in the fuel delivered to one or more engine cylinders but will move through the sequential injections to all of the cylinders. For example, engine failures due to consistentlylean mixtures on one cylinder of the engine are prevented. While excessively rich or lean injections could occur due to manufacturing differences; these conditions will move through all of the cylinders of the multicylinder engine.

The bearing 25 for the pump shaft 24 and the pump pistons are lubricated through a lubrication connection 2 6 in the housing and lubricant flows through suitable passages through a passage 27 to the bearing 25 and through passages such as 28 leading to the individual pump pistons and their seals. Lubricant is also delivered to the hollow chamber 33 which contains the mechanism for driving the pump pistons.

As shown in FIGURES l and 3, the pump is provided with three radially extending pistons 29, and 31 slidably supported in radially bored cylinders 29a, 30a and 31a in the housing 16. An odd number of pistons are provided and a greater number may be employed if desired retaining an odd number. The pistons are movable radially outwardly in a discharge stroke and radially inwardly in an intake stroke and are urged inwardly by springs such as 32 surrounding the inner ends of the pistons and seated in annular recesses in the wall of the chamber 31. Split snap rings 34 seat in annular grooves in the pistons to hold washers against which the springs engage. Inasmuch as the construction of each piston is the same, the arrangement of the piston 30 only need be described in detail.

The pistons are driven by a head 35 eccentrically carried at the lower end of the pump shaft 24. The head 35 rotatably supports a roller 36 which is rotatably mounted on a stud 35a on the head and the roller 36 rolls on the stud to reduce friction between the roller and pistons.

The head 35 is carried in a radially exending supporting slot 37 on the shaft 24 and its eccentricity with respect to the axis of the shaft is controllable by a bell crank 38 supported on the shaft. The lower arm of the bell crank is held in a recess 39 in the head 35 and the upper arm of the bell crank 39 is received in a recess 40 in a plunger 41 coaxially carried in the hollow center of the pump shaft 24. A cross pin 41a extends across through an axially elongated slot 41b in the plunger 41'and the pin 41a is mounted in the shaft 24. This pin 41a also functions to lock the gear 23 to the pump shaft. A spring 42 in an axially extending recess in the end of the shaft 24 engages the underside of an enlarged head 410 of the plunger 41 to urge it to the left, as shown in FIGURE 1. This tends to move the head 35 to increase the eccentricity thereof and increase the pump delivery. The action of the spring 42 is resisted by an arm 43 hearing on the upper end of the head of the plunger 41 and mounted on a shaft 44. The shaft 44 is connected to a fuel control mechanism, not shown, which operates a rod 13', FIGURE 4, to operate the shaft 44.

The fuel control mechanism will determine the displacement and output of the metering pump 10 and is operated in accordance with various factors of engine conditions such as the intake manifold pressure and engine temperature, as will be fully appreciated by those skilled in the art and therefore need not be shown. A, manual input signal is also provided by an accelerator, not shown.

Each of the pump plungers are sealed by an O-ring 47 in an annular groove 47a in the housing. The width of the groove in an axial direction is greater than the cross sectional diameter of the O-ring. The inner diameter of the elastic O-ring is slightly greater than the diameter of the piston 30 and the outer diameter of the O-ring is slightly greater than the diameter of the base of the groove 47a. When assembled, the radial compression of the outer diameter of the elastic O-ring forces the inner diameter of the ring to contact the cylindrical piston surface. Dimensions of the O-ring, O-ring groove, and piston are so designed that contact of the inner diameter of the O-ring with the piston is sufiicient to seal against the fluid fuel pressure but light enough to prevent excessive friction during reciprocation of the piston Within the seal. The cylindrical bore or cylinder 30a in which the piston slides is relieved at its outer end so as to be of a slightly larger size than the inner end to thereby prevent scratching of the piston at the location where the piston slides through the O-ring 47. This insures that the piston will retain its finish at that location and not wear the O-ring but retain a good seal. Lubricant enters the cylinder 30a behind the O-ring seal.

As shown in FIGURES 1 and 3, the fuel enters the intake 18 of the housing and flows through a passage 49 that forms a loop. Off this loop are branch passages 50, 51 and 52 for supplying pumping chambers 48 at the end of the pump pistons.

chambers 48 flows through an intake port 51a past a check valve, FIGURES 1 and 7, having a ball check 53 held by a spring 54 against a seat 55 so as to close the intake passage when the pump piston moves outwardly. Flow out of the pumping chamber 48 is through a port 56a past a ball check valve 56b which closes during the intake, stroke of the piston. The ball check valve 56b held Fuel intake into the pump against a valve seat 560 by a spring 56d is also shown. Instead of ball valves 53 and 56b resilient flap valves may be employed. The pumping chambers 48 and the check valves are conveniently contained in housing projections 16a, FIGURES 1 through 4, mounted on the housing at the ends of each of the pump pistons.

Delivery from the pumping chamber 4-? is through a passage 56 leading up into a chamber 57 in which is located a distributor plate 58. The passage 56 and the chamber 57 constitute the conduit means leading from the pump discharge to the distributor.

It is to be noted that the pumping chamber receives fluid through the port 51a and delivers fluid through the port 56a. These ports and the passageways connected thereto are arranged so that fluid flow through the pumping chamber 48 is in an upward direction thus facilitating the escape flow of fluid vapor and entrained air through the chamber. All of the fluid passages in the pump are designed to prevent the trapping of fuel vapor or entrained air in the pumping elements. This makes the pump self-purging of vapor and air and greatly reduces the number of pump revolutions required to purge a vapor locked pump.

As shown in FIGURES 1 and 2, a distributor plate 58 has a fiat smooth undersurface which sealingly slides against a surface 59 in the chamber 57 and is held downwardly by a spring 60 and is driven by the shaft 17. Below the distributor plate 58 in the stationary housing part area series of evenly spaced circumferentially arranged relief ports 62 which conduct fuel each time an elongated port 61 in the distributor plate 58 passes over them. This intermittently at even intervals relieves the fluid fuel from the distributor chamber 57 and the fuel sequentially flows out through the lines 19 to the individual injectors 14. Y

The accumulator 13 which is in communication with the conduit means 12 between the pump and distributor has an expansible chamber in the form or" a cylinder 63 in which is located a piston 64-. The piston is spring loaded by a spring 66 which urges the piston 64 in a direction to discharge the fuel from the chamber 63. An annular piston seal 65 surrounds the piston.

The spring 66 has a natural frequency greater than the accumulator exciting frequency, namely the opening and closing of the successive distributor ports. The accumulator thus empties itself for each release of the distributor.

The accumulator 13 is located below the distributor chamber and in a position so that air or fuel vapor cannot be trapped. The cylinder 63 is shown in a horizontal position below the distributor.

Also in communication with the distributor chamber 57, or in other words, in communication with the conduit means 12 between the pump and distributor, is an accelerator chamber shown in the form of an elongated cylinder 67. The chamber 67 communicates with the distributor chamber 57 through openings 72 through the distributor plate. Within the chamber 67 is a piston 68 having a piston ring 69. The piston is mounted on a piston rod 7% suitably connected to the accelerator pedal, not shown.

Movements of the accelerator pedal to decelerate allow the chamber 67 to fill from fuel delivered by the pump 19; As the accelerator is moved in an accelerating direction, the piston 63 will force fuel out of the chamber 67 through the openings 72 which will cause the distributor to deliver an increased quantity of fuel to the engine. The distributor plate 58 is held down against its smooth surface 59 by a coil spring 6i and the flow of fuel through the passages 72 have no effect on the normal operation of the distributor.

The use of this accelerator chamber 67 enhances the response of the engine to movements of the accelerator pedal without adding to the flow rate through the variable displacement pump 10. This therefore occurs without sacrifice to the general fuel economy. It is also to be noted that as the accelerator is released, the variable chamber 67 provides an escape chamber for the fuel in the distributor thereby enhancing the rapid cut-off of fuel supplied to the engine as the accelerator is released to prevent delivering over enriched fuel to the engine and consequent smoking and increase in smog effects.

While the fuel injection nozzles may be of various designs, the nozzle 14 is shown schematically as including an injection opening 74 against which seats a valve member 73 held against the opening by a tension spring '75. The tension spring 75 is such that it opens at a lower fuel pressure than that required to depress the accumulator spring 66. Thus with the accumulator discharge pressure being greater than the injector nozzle opening pressure, the injector will open as soon as the distributor 11 releases the fuel and will stay open during the time the accumulator piston 64 is emptying the accumulator chamber and during the time the distributor ports are in alignment.

The multiple piston metering and pressure generating pump has an advantage in freedom from high speed limitations that are placed on a single piston injection pump that must reciprocate through one stroke for each cylinder of a multi-cylinder engine. The metering pump with a rotary distributor has considerable manufacturing advantages over types heretofore used requiring individual pistons, cylinders, valves and passages all of which must be precisely matched to maintain distribution equality for each cylinder of a multicylinder engine.

The rotating distributor of the unit is normally driven at half engine crank shaft speed toprovide one injection per four stroke cycle of the typical multicylinder engine. The metering and pressure generating pump is gear driven from the rotary distributor shaft at a speed selected to best suit several factors, although preferably driven at a speed ratio which is not an exact whole number, as above described. The factors which determine the speed at which the pump is driven include pump performance efiiciency and endurance reliability and the maximum delivery required by the particular engine displacement. pump unit may be used to accommodate engines of different sizes. For example, to accommodate a passenger car engine, a pump constructed as shown but using five pistons was geared to make 455 piston strokes for every two-engine revolutions. An identical unit was used to fuel a much larger displacement engine by employing a gear ratio that provided 5.5 piston strokes per two-engine revolutions.

The versatility of the system is shown in the pumping unit illustrated wherein three pistons are employed for the pump. By changes in piston diameter, maximum.

piston stroke, and pumping element driving gears, a three piston pump is capable of fueling a small displacement (140 cubic inch) compact car engine or a large displacement (540 cubic inch) light aircraft engine. Cast housings, mechanical linkages and controls for the range of engine sizes remain identical effecting advantages in servicing, assembly, and reduction of manufacturing costs.

. It will be understood that while the distributor usually is employed to accomplish one fuel release and one injection per four stroke cycle it may also be used to provide two injections per four stroke cycle. This method of distribution halves the large fuel quantities required per cycle and precludes the necessity for larger metering pump components.

In the starting fuel enrichment apparatus shown in FIGURE 4, the control rod 13' for controlling the output of the metering pump 10 is mechanically connected to the shaft 44. A pivotal arm 76 is connected to shaft 44, and to a link 77 which is connected between the ends of an arm 78. One end of the arm 78 is connected to the control rod 13' and the other end is connected to a rod 79 connected to a bellows 80. The bellows 80 is in a A significant advantage is that the same closed chamber 81 maintained at intake manifold pressure through a line 82. The control rod 13 is operated by the solenoid 12', but can be operated by various parameters of engine operation such as by being connected to a device responsive to engine oil pressure. The rod 13' is shown as urged to the left in FIGURE 4 by a spring 83 which moves the rod 13' to decrease the pump output.

During running of the engine the spring 83 urges the rod 13' to the left, as shown in FIGURE 4, so that a collar 84 on the rod engages a stop 14'. Control of the fuel pump is obtained by variation in intake manifold pressure which moves the bellows rod 79 through an op erating range of movement.

When the engine is started, a starting switch 85 is closed to close a circuit to a starter motor 85a, and this also energizes the solenoid 12 to move the control rod 13' to thereby obtain full capacity output of the pump. The pump and pump control are then operating in the starting range. As soon as the starter switch 85 is opened, the spring 83 returns the rod 13' to normal running position, so that the pump and control are then within a normal operating range. In other words, the structural arrangement of FIGURE 4 functions so that during normal running the arm 76 is moved through an operating range of .movement, and even at maximum operating output, which isin the operating range, the delivery of the pump will be considerably less than its full delivery. During starting, the structure of FIGURE 4 operates to shift the pump control beyond the operating range of movement to the starting range, and thereby obtains full capacity output of the pump. It will be recognized, of course, that devices other than that shown in FIGURE 4 may accomplish the foregoing operation, although the arrangement of FIGURE 4 provides certain functional advantages.

, Thus a pump is provided with an excess capacity and only a small proportion of the total capacity is used in i the normal operating range. In normal operation, the pump is regulated by a control movable between cut-oif position and full power position, and at starting the control is movable to a maximum delivery position which is past full power position.

In the starting fuel enrichment arrangement of FIG- URE 6, the supply pump 15 is connected so that its output is delivered to the intake 18 of the pump distributor housing 16.-. The supply pump is driven .by an electric motor 87 shown as connected by leads 87a to a source of electrical power such as a battery 91 through a switch 87b, although other suitable pump driving means may be employed. The supply pump thus is capable of full delivery as soon as the motor 87 is started and usually it. will be connected to the ignition switch for the engine. The supply pump usually delivers fuel to the metering pump 10 at a substantially constant pressure on the order of 25. to 30 pounds per square inch during normal opera-.

tion and has a constant discharge rate with the excess fuel being returned to a fuel tank 86.. The pressure is maintained at this level. by delivering the excess fuel through the by-pass line 16" which contains a pressure regulating valve 88. Also interposed in the by-pass re-- turn line 16is theby-pass shut-off valve 17' which restricts the bypass flow for short periods suchras during the cranking cycle to cause the .supply pump output 7 pressure to build up on the order of pounds per square inch. The by-pass restricting valve 17 is operated by a solenoid 89 connected .to be energized when a starter switch 90 is .closed to operate the starter. motor 92.

-The injector nozzles 14 are adjusted to open at a pressure between the normal supply pressure of the supply pump and the short term maximum output pressure, so that when the by-pass restricting valve 17' is closed the supply pump .15 willdeliver fuel directly through the distributor and through. the injection nozzles independent of the metering pump- This will of course increase the fuel supply flow to the engine for enrichment during starting. It will also flush fuel through the pumping chambers 48 of the metering pump thus removing vapor and air pockets which may form during the. times when the engine is not operating. 7

The metering pump arrangement and. distributor permit direct delivery from the supply pump 15' to the nozzles inasmuch as the flow at increased pressure will open the check valves 53 and 56b and flow directly through the pump chamber .48 to the distributor, flowing through the conduit means 12.

The increased pressure of the supply pump, as during the cranking cycle, does not present an undue hardship on the supply pump that must continuously maintain a supply pressure on the order .of 25 to 30 pounds per square inch during normal engine or over the road operation.

While both of the above starting methods as shown by the apparatus of FIGURES 4 and 6 were devised for cold weather starting, they are also extremely useful for very hot weather starting conditions that normally results in fuel vapor accumulations within the system. Both methods provide vapor purging flows through the meter ing pump piston chambers during the cranking period.

Both methods for providing cranking enrichment will be provided with an override control to be commercially practical. FIGURES 4 and 6 illustrate an override control operated by the accelerator foot pedal, shown at 94 and 94 respectively in FIGURES 4 and 6. The electrical lines to the solenoids 12 and 89 are provided with normally closed spring loaded switches 93 and 93 respec tively, and these switches are opened by rods 95 and 95", connected to the accelerator pedals, when the accelerator pedals are fully depressed. In the arrangement shown, maximum depression of the foot pedal opens the switch contacts. 'Other arrangements could be used such as a structure for mechanically restraining the control rod 13' of FIGURE 4, returning it to normal operating range of movement. The override feature is required to clear a fuel flooded engine which will not start. 7

As a brief summary of operation, the operator closes the pump switch 871) in FIGURE 6,- and the starting switch 85 in FIGURE 4, or 90 in FIGURE 6 (these are the same switches where both methods are combined in a single system) and the solenoid motor 12'. of FIGURE 4 moves the control rod 13 to establish maximum displacement setting for the pump 10. The by-pass valve 17 of FIGURE 6 is closed to either close off or largely restrict the flow through the return line 16 causing the supply pump to have an increased pressure to deliver fuel directly through the pump chamber 48, FIGURE 1, and open the valves of the injectors 14 for direct delivery of fuel for each distributor release. As soon as the engine is started, the control rod 13' is released, and/or the by-pass valve 17 is opened, and the pump 10'is controlled for displacement in its normal operating range. Fuel is delivered by the metering pump 10 through the conduit means 12 to the distributor where it is released intermittently to the injectors 14, with fuel being accumulated in the accumulator 13 between distributor releases and being released to the injectors during the release period.

Thus it will be seen that we have provided an improved fuel injection system having an arrangement for selectively enriching fuel delivery to an engine which meets the objectives and advantages above set forth.

The mechanism provides'a metering pump delivering to a distributor with a mechanism for selectively deliver- 7 ing fuel to the distributor independent of the metering pump for enrichment. The enrichment fuel is delivered in large quantities through the pump chambers of the pump for purging vapor and air during cranking.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications, changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

We claim as our invention:

1. A fuel supply mechanism for a fuel injection engine comprising a metering pump having a pumping chamber with an intake passage and a discharge passage, a supply pump connected to said intake passage for delivering fuel from a tank, a supply pump pressure regulating by-pass line connected to the supply pump returning fuel not used by the metering pump back to the tank, a pressure regulating valve interposed in said line opening to control the normal delivery pressure of the supply pump, a shut-off by-pass valve interposed in said line for selectively cutting oif by-pass flow and increasing delivery pressure of the supply pump to a maximum pressure, a fuel distributor connected to the discharge passage of the metering pump for distributing the fuel to injectors, and fuel injectors connected to the distributor and having an opening resistance pressure greater than said normal output pressure of the supply pump determined by said regulating valve and less than said maximum delivery pressure so that fuel will flow freely through the pumping chamber overcoming the resistance of said injectors to be released by the distributor and discharged by the injectors when said bypass valve is closed.

2. A fuel supply system for a fuel injection engine comprising,

fuel injectors having a predetermined release pressure,

a distributor connected to said injectors for cyclically delivering fuel to individual injectors,

a metering pump means metering the quantitiy of fuel and connected to deliver fuel to said distributor at a pressure greater than said injector release pressure,

and a fuel enrichment means connected directly to the distributor and having a delivery pressure in excess of said predetermined release pressure for delivering fuel to the distributor directly during enrichment periods.

3. A fuel supply system for a fuel injection engine comprising,

fuel injectors having a predetermined release pressure,

a distributor connected to said injectors for cyclically delivering fuel to individual injectors,

a metering pump means metering the quantity of fuel and connected to deliver fuel to said distributor at a pressure greater than said injector release pressure,

a fuel supply pump means connected to deliver fuel through said metering pump means to said distributor at a normal pressure less than said predetermined release pressure of said injectors,

and means increasing the output pressure of said supply pump means to greater pressure than said release pressure so that fuel is delivered to the distributor from said supply pump and discharges from said fuel injectors.

4. A fuel supply mechanism for a fuel injection engine comprising a metering group having a pumping chamber with an intake passage and a discharge passage,

spring loaded check valves in said passages for closing the intake and discharge passages during discharge and intake respectively of the pump,

a supply pump connected to said intake passage having a discharge pressure delivering unmetered fuel from a tank to the metering pump overcoming said check valve in said inlet passage,

a supply pump pressure regulating by-pass line connected to the supply pump returning fuel delivered by the supply pump not used by the metering pump back to the tank,

a fuel distributor connected to the discharge passage of the metering pump for distributing the fuel to injectors,

and a valve interposed in said by-pass line for selectively restricting the flow of fuel back to the tank so that unmetered fuel will be delivered directly through said pumping chamber. to the distributor. 5. A fuel supply mechanism for a fuel injection engine comprising a metering pump having a pumping chamber for the intake and discharge of fuel,

injection nozzles having a predetermined tinjection release pressure,

a distributor connected to said chamber of the metering p p a supply pump means connected to said chamber of the metering pump,

having a normal output pressure less than said predetermined injection release pressure insufficient to force fuel through the distributor to open injectors to which the distributor delivers fuel,

and means operative independent of the speed of the engine for increasing the output pressure of the supply pump means greater than said predetermined release pressure to force fuel through the distributor and open the injectors and increase the fuel delivery.

6. A fuel supply system for a fuel injection engine comprising,

a metering pump having a pumping chamber for the intake and discharge of fuel,

fuel injector nozzles having a predetermined release pressure being less than the discharge pressure of said metering pump,

a fuel distributor passage means communicating with said pumping chamber and successively connecting said metering pump to said injectors,

a supply pump means connected to deliver fuel directly to said pumping chamber and having a normal output pressure less than said release pressure of the injectors,

check valve means connected between the supply pump means and the metering pump chamber preventing flow of fuel from the chamber toward the supply pump means thereby preventing the discharge of fuel from the metering pump from flowing back to the supply pump means and insuring positive delivery from the metering pump to said closed fuel distributor passage means,

and means independent of engine speed for increasing the discharge pressure of said supply pump means to a pressure in excess of the release pressure of the injectors and in excess of the resistance of said check valve means so that unmetered fuel will fiow directly from the supply pump means to the distributor passage means. 7

7. A fuel supply mechanism for a fuel injection engine comprising,

a metering pump having a pumping chamber with an intake passage and a discharge passage,

an intake check valve in said intake passage closing upon discharge of the metering pump,

a supply pump connected to the intake passage having a discharge pressure less than the metering pump so that the intake check valve closes against the output pressure of the supply pump during pump- References Cited by the Examiner UNITED STATES PATENTS (Other references on foilowiug page) 9/43 Curtis l035 X' 11 UNITED STATES PATENTS Dolza et a1 123-119 Foddy et a1. 123-179 Pringham 1035 X Dolza 123-439 5 Scherenberg et a1 123-179 Nystrom et a1 123-179 2,965,089 12/60 Holley 123-439 3,020,905 2/62 Goschel 123-179 FOREIGN PATENTS 697,616 9/53 Great Britain.

RICHARD B. WILKINSON, Primary Examiner.

DON A. WAITE, Examiner. 

2. A FUEL SUPPLY SYSTEM FOR A FUEL INJECTION ENGINE COMPRISING, FUEL INJECTORS HAVING A PREDETERMINED RELEASE PRESSURE, A DISTRIBUTOR CONNECTED TO SAID INJECTORS FOR CYCLICALLY DELIVERING FUEL TO INDIVIDUAL INJECTORS, A METERING PUMP MEANS METERING THE QUANTITY OF FUEL AND CONNECTED TO DELIVER FUEL TO SAID DISTRIBUTOR AT A PRESSURE GREATER THAN SAID INJECTOR RELEASE PRESSURE, AND A FUEL ENRICHMENT MEANS CONNECTED DIRECTLY TO THE DISTRIBUTOR AND HAVING A DELIVERY PRESSURE IN EXCESS OF SAID PREDETERMINED RELEASE PRESSURE FOR DELIVERING FUEL TO THE DISTRIBUTOR DIRECTLY DURING ENRICHMENT PERIODS. 